The present invention relates to a guide wire for use in a re-canalising process of a vascular occlusion in a human or animal subject, and in particular, for re-canalising a blocked or partially blocked artery, for example, in the cardiovascular system, although the invention is not limited to a guide wire for such use. The invention also relates to a method for re-canalising a vascular occlusion in a human or animal subject.
Guide wires are commonly used for guiding a catheter carrying a therapeutic or other device to a remote location in the vascular system of a subject. For example, where a vessel is occluded or partially occluded, a guide wire is used for guiding a catheter which may carry a balloon or a stent at its distal tip for locating in the artery in the occluded part thereof for maintaining a passage through the occlusion. However, prior to the insertion of the stent or other such device, the occlusion must be penetrated in order to open a passage therethrough for accommodating the stent.
Guide wires are provided for penetrating such occlusions or partial occlusions prior to the insertion of the catheter over the guide wire. U.S. Pat. No. 6,348,040 of Stalker, et al discloses such a catheter which is provided with a vibrating tip. However, a disadvantage of the guide wire disclosed in this U.S. patent specification is that in order to provide the vibrating tip, relatively expensive and, more importantly, cumbersome equipment is required, which must be attached to the guide wire
U.S. Pat. No. 6,669,652 of Anderson, et al discloses a guide wire, which comprises a core wire and a helical coil extending around a distal portion of the core wire. The helical coil extends beyond the distal end of the core wire, and tapers to a distal point for penetrating the occlusion as the guide wire is urged forwardly. One disadvantage of the guide wire disclosed in this U.S. specification is that due to the fact that the tip is pointed, there is a danger of the tip penetrating the wall of a vessel of the vascular system as the guide wire is being urged to the occlusion. Another disadvantage of this guide wire is that the portion of the helical coil which extends beyond the distal end of the core wire is relatively flaccid, and thus renders the guide wire difficult to guide through the vascular system, and in particular a vascular system with branched vessels.
U.S. Pat. Nos. 5,527,298 and 5,127,917 disclose guide wires in which the distal end of the guide wires terminate in bulbous distal tip portions. The distal tip portions are of transverse cross-sectional area significantly greater than the transverse cross-sectional area of the guide wire, and taper to a distal point. The distal point facilitates penetration of the occlusion, and the tapering portion facilitates in easing the guide wire through the occlusion. However, a disadvantage of the guide wires disclosed in these two U.S. patent specifications is that due to the fact that the transverse cross-sectional area of the bulbous distal tip portions are significantly greater than the transverse cross-sectional area of the guide wire, difficulty is experienced in subsequently urging a catheter over the bulbous tip portions.
There is therefore a need for a guide wire which is suitable for use in a re-canalising process of a vascular occlusion in a human or animal subject.